The goal of this project is to better understand the relationship of patient status (severity, comorbidity, demographic factors) and appropriateness of care to a symptomatic outcome. Further, it examines the relationship of the symptomatic outcome. Further, it examines the relationship of the symptomatic outcomes on subsequent utilization for the same and similar problems as identified in an administrative database. The two problems studied are cholecystectomy and total hip arthroplasty. Specifically it seeks to answer: 1) What role do comorbid factors and severity of illness have on sysmptomatic relief from cholecystectomy and THA and for functional status for THA? 2) Are good symptomatic outcomes for cgolecystectomy evidence of better process as measured by compliance with appropriateness criteria? 3) Do better symptomatic outcomes from cholecystectomy and symptomatic and functional outcomes from total hip arthroplasty predict subsequent utilization and can one infer symptomatic and functional outcomes from utilization? The project uses an existing database, the information collected as part of the Post Hospitalization Outcomes Studies, a large HCFA sponsored study of outcomes after hospitalization for cholecystectomy and total hip arthroplasty in Medicare patients. This project merges this data with subsequent utilization data obtained from HCFA for the same patients. Using regression and other techniques the effects of patient status on symptomatic outcome will be studied. Using similar techniques the relationship of appropriateness ofcare for outcomes of cholecystectomy will be studied. Finally, using regression and other techniques the relationship of symptomatic outcome to utilization will be examined and the ability of utilization to serve as a surrogate outcome wil be addressed.